WebMD talks to dermatologists about sunscreen safety, ingredients, and labels.

Sunscreen Safety: What to Know

Sunscreen ingredients, labels, and more.

Sunscreen Hazards continued...

Oxybenzone: Oxybenzone, a common UV filter, has been shown to interact with hormones when fed to animals in large amounts. Dermatologists say this is no reason to toss your sunscreen.

"If you covered your entire body with oxybenzone in the concentrations that are in sunscreens and used it every day, it would take over 30 years to get to the point of what these rats were fed in these studies," says dermatologist Darrell Rigel, MD, FAAD, who is a clinical professor of dermatology at New York University Langone Medical Center.

They used to go on thick and white like an ointment for diaper rash. In fact, zinc oxide is the main ingredient in baby ointments. So they weren't the most popular sunscreens. You only saw them on lifeguards' noses.

Now there are mineral sunscreens in which the particles have been shrunk to micro or nano-size to become colorless on the skin.

Can nanoparticles get past the skin's surface and into the body? There is still debate about whether they get into the body and, if so, what effects they might have.

"You want to avoid any sunscreens that have nanoparticles," Jaliman says. "They are showing up in the liver and in the bloodstream, and they are banned in a lot of places."

However, Lim says we don't know for sure when these nanoparticles can sink below the skin's surface.

"We know that with intact skin, nanoparticles will stay on top of the skin. What is not known is if the skin is broken, for example with eczema, would nanoparticles go in? That part we don't have a good answer for," Lim says.

If you are concerned, check the labels. Look for "non-nano" under active ingredients. However, sunscreens are not required to note whether they include nanoparticles.

The AAD and the Skin Cancer Foundation have reviewed studies that suggest these ingredients are dangerous. They, along with the FDA, continue to stand behind the ingredients. The Personal Care Products Council, a trade group, also backs these ingredients.